1.
I am guessing this is for simple interest.
S.I = PRT
P for Principal Amount
R for Rate
T for Time in years
I = £4500 × 0.04 × 2
(0.04 = [tex] \frac{4}{100} [/tex] = 4%)
I = £360
The total amount will be 4500 + 360 = £4860
2. 20% off, £220
Original price?
original price × 0.2 = 220
(0.2 = [tex] \frac{20}{100} [/tex] = 20%)
Divide by 0.2 on either sides to find the original price
[tex] \frac{original price * 0.2}{0.2} = \frac{220}{0.2} [/tex]
0.2 and 0.2 cancels out
original price = £1100
check:
0.2 × 1100 = £220
